Due to increased competition in the fast food industry, various types of food items have recently been introduced to the public. Many of these food items are intended to be eaten at the point of purchase while the food item is still warm. However, a significant percentage of food items that are sold are intended to be eaten at a later time, such as in an office or factory environment, or while traveling in a motor vehicle.
Disposable bags for packaging warmed fast food items are generally not provided with heat insulation, and quickly cool, to such an extent that the food items lose their appeal, including flavor and aroma. The inherent appeal of some of these recently introduced food items, or of well known food items such as baked goods, French fries and several types of sandwiches, is also associated with their crispiness. If such crispy food items are eaten at a later time, the residual oil or grease condensates, causing the food items to lose their external crisp texture and become soggy.
U.S. Pat. No. 6,187,396 discloses a bag for wrapping food items which is formed of a composite material including a first layer of cellulose-containing material and a second layer made of polyethylene. The composite material is formed with perforations that are pierced through the two layers. The ratio of open area to total area of the composite material is selected to maintain a controlled exchange of moisture from the interior to exterior of the bag.
Although this perforated bag is effective in terms of releasing a desired amount of moisture therefrom, which would condense if not released and compromise the crispiness of a food item, while preventing an excessive amount of moisture release, which would cause a baked good such as bread to become stale, the bag is ineffective in terms of retaining the warmth of the food item contained therein. A warm food item placed within the bag transfers heat by convection to the surrounding air within the bag. Since the perforations are pierced through the two layers of the composite material, the convected air, in addition to moisture, is released to the exterior of the bag via the perforations, thereby quickly cooling the food item.
U.S. Pat. No. 5,346,312 discloses a bag for maintaining cooked foods in a hot, crisp condition. The bag has a multi-ply film composite comprising a nonporous outer film ply made from a thermoplastic material and an inner porous film ply consisting of a blend of polyolefins. The plies are spaced so as to provide a gap in the form of a fluid reservoir for collecting and separating fluids from the food, in order to maintain food crispiness. The enclosed air space between adjacent film plies helps to limit heat loss from the food.
It would be desirable that fast food items be prepackaged, in order to achieve fast delivery of fast food items to consumers and efficient utilization of employees of a fast food enterprise. The preparation of many food items is time consuming, involving for example frying meat, cutting vegetables, and placing the same in a bun. The manipulation of a greasy food item is often more cumbersome, and is therefore even more time consuming. It is therefore desirable that the fast food items be prepared during periods of low customer volume, such as in the early morning hours, packaged in a suitable bag, and cooled in a refrigerator or frozen, whereupon the bags containing prepackaged food items are removed from cold storage and heated in an oven or in a microwave oven upon demand or during periods of high customer volume without involving a relatively long delay to a customer.
The bags of U.S. Pat. No. 6,187,396 and U.S. Pat. No. 5,346,312 are made of a thermoplastic material and therefore are not suitable for being heated in an oven or in a microwave oven. Additionally, thermoplastic materials are not biodegradable and involve cost expenditures for recycling these materials.
U.S. Pat. No. 3,628,720 discloses a bag having two plies of plastic sheet material, each ply having perforations which are offset from the perforations in the other ply. The perforations have the form of a tapered nozzle with its tapered end directed in the desired direction of air passage.
It is an object of the present invention to provide a bag and method for retaining the warmth and crispiness of food items containing therein for a useful period of time after delivery to a consumer.
It is an additional object of the present invention to provide a bag for packaging warmed fast food items that is disposable and biodegradable.
It is an additional object of the present invention to provide a bag for packaging warmed fast food items that can be heated in an oven or in a microwave oven.
It is yet an additional object of the present invention to provide a process for producing a bag in a simple, quick and economical manner.
Other objects and advantages of the invention will become apparent as the description proceeds.